| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <b2e84054-bf3b-4a1a-b946-bd024f341512@kylinos.cn>
Date: Sat, 20 Dec 2025 13:43:46 +0800
From: Enze Li <lienze@...inos.cn>
To: Huacai Chen <chenhuacai@...nel.org>, yuan linyu <yuanlinyu@...or.com>
Cc: Alexander Potapenko <glider@...gle.com>, Marco Elver <elver@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>, Andrew Morton
<akpm@...ux-foundation.org>, WANG Xuerui <kernel@...0n.name>,
kasan-dev@...glegroups.com, linux-mm@...ck.org, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org, enze.li@....com
Subject: Re: [PATCH v2 1/2] LoongArch: kfence: avoid use
CONFIG_KFENCE_NUM_OBJECTS
On 2025/12/19 10:13, Huacai Chen wrote:
> Hi, Enze,
>
> On Thu, Dec 18, 2025 at 2:39 PM yuan linyu <yuanlinyu@...or.com> wrote:
>>
>> use common kfence macro KFENCE_POOL_SIZE for KFENCE_AREA_SIZE definition
>>
>> Signed-off-by: yuan linyu <yuanlinyu@...or.com>
>> ---
>> arch/loongarch/include/asm/pgtable.h | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
>> index f41a648a3d9e..e9966c9f844f 100644
>> --- a/arch/loongarch/include/asm/pgtable.h
>> +++ b/arch/loongarch/include/asm/pgtable.h
>> @@ -10,6 +10,7 @@
>> #define _ASM_PGTABLE_H
>>
>> #include <linux/compiler.h>
>> +#include <linux/kfence.h>
>> #include <asm/addrspace.h>
>> #include <asm/asm.h>
>> #include <asm/page.h>
>> @@ -96,7 +97,7 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
>> #define MODULES_END (MODULES_VADDR + SZ_256M)
>>
>> #ifdef CONFIG_KFENCE
>> -#define KFENCE_AREA_SIZE (((CONFIG_KFENCE_NUM_OBJECTS + 1) * 2 + 2) * PAGE_SIZE)
>> +#define KFENCE_AREA_SIZE (KFENCE_POOL_SIZE + (2 * PAGE_SIZE))
> Can you remember why you didn't use KFENCE_POOL_SIZE at the first place?
I don't recall the exact reason off the top of my head, but I believe it
was due to complex dependency issues with the header files where
KFENCE_POOL_SIZE is defined. To avoid those complications, we likely
opted to use KFENCE_NUM_OBJECTS directly.
I checked out the code at commit
(6ad3df56bb199134800933df2afcd7df3b03ef33 "LoongArch: Add KFENCE (Kernel
Electric-Fence) support") and encountered the following errors when
compiling with this patch applied.
8<------------------------------------------------------
CC arch/loongarch/kernel/asm-offsets.s
In file included from ./arch/loongarch/include/asm/pgtable.h:13,
from ./include/linux/pgtable.h:6,
from ./include/linux/mm.h:29,
from arch/loongarch/kernel/asm-offsets.c:9:
./include/linux/kfence.h:93:35: warning: 'struct kmem_cache' declared
inside parameter list will n
ot be visible outside of this definition or declaration
93 | void kfence_shutdown_cache(struct kmem_cache *s);
| ^~~~~~~~~~
./include/linux/kfence.h:99:29: warning: 'struct kmem_cache' declared
inside parameter list will n
ot be visible outside of this definition or declaration
99 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t
flags);
| ^~~~~~~~~~
./include/linux/kfence.h:117:50: warning: 'struct kmem_cache' declared
inside parameter list will
not be visible outside of this definition or declaration
117 | static __always_inline void *kfence_alloc(struct kmem_cache *s,
size_t size, gfp_t flags)
| ^~~~~~~~~~
./include/linux/kfence.h: In function 'kfence_alloc':
./include/linux/kfence.h:128:31: error: passing argument 1 of
'__kfence_alloc' from incompatible p
ointer type [-Wincompatible-pointer-types]
128 | return __kfence_alloc(s, size, flags);
| ^
| |
| struct kmem_cache *
./include/linux/kfence.h:99:41: note: expected 'struct kmem_cache *' but
argument is of type 'stru
ct kmem_cache *'
99 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t
flags);
| ~~~~~~~~~~~~~~~~~~~^
------------------------------------------------------>8
Similarly, after applying this patch to the latest code
(dd9b004b7ff3289fb7bae35130c0a5c0537266af "Merge tag 'trace-v6.19-rc1'")
from the master branch of the Linux repository and enabling KFENCE, I
encountered the following compilation errors.
8<------------------------------------------------------
CC arch/loongarch/kernel/asm-offsets.s
In file included from ./arch/loongarch/include/asm/pgtable.h:13,
from ./include/linux/pgtable.h:6,
from ./include/linux/mm.h:31,
from arch/loongarch/kernel/asm-offsets.c:11:
./include/linux/kfence.h:97:35: warning: 'struct kmem_cache' declared
inside parameter list will n
ot be visible outside of this definition or declaration
97 | void kfence_shutdown_cache(struct kmem_cache *s);
| ^~~~~~~~~~
./include/linux/kfence.h:103:29: warning: 'struct kmem_cache' declared
inside parameter list will
not be visible outside of this definition or declaration
103 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t
flags);
| ^~~~~~~~~~
./include/linux/kfence.h:121:50: warning: 'struct kmem_cache' declared
inside parameter list will
not be visible outside of this definition or declaration
121 | static __always_inline void *kfence_alloc(struct kmem_cache *s,
size_t size, gfp_t flags)
| ^~~~~~~~~~
./include/linux/kfence.h: In function 'kfence_alloc':
./include/linux/kfence.h:132:31: error: passing argument 1 of
'__kfence_alloc' from incompatible p
ointer type [-Wincompatible-pointer-types]
132 | return __kfence_alloc(s, size, flags);
| ^
| |
| struct kmem_cache *
./include/linux/kfence.h:103:41: note: expected 'struct kmem_cache *'
but argument is of type 'str
uct kmem_cache *'
103 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t
flags);
| ~~~~~~~~~~~~~~~~~~~^
------------------------------------------------------>8
So, this patch currently runs into compilation issues. linyu probably
didn't have KFENCE enabled when compiling locally, which is why this
error was missed. You can enable it as follows:
Kernel hacking
Memory Debugging
[*] KFENCE: low-overhead sampling-based memory safety
Thanks,
Enze
<...>
Powered by blists - more mailing lists